OX40:OX40L interaction – evolving from a key component of autoimmunity to a possible target for cardiovascular disease

DailyUpdates Jan 31st: OX40:OX40L interaction – evolving from a key component of autoimmunity to a possible target for cardiovascular disease

OX40 (CD134) is one of the newer tumor necrosis factor receptor (TNFR) family members. Expressed on CD4+ T-cells, its activation by OX40L, a type II membrane protein expressed on activated B-cells, dendritic cells and macrophages, plays an important T-cell co-stimulatory role.

In our recent feature on Autoimmune Disorders & Transplant Rejection we describe the proof of concept for interrupting OX-40 activation as a candidate treatment for a number of autoimmune diseases. For example, blocking OX40/OX40L interactions prevents islet destruction and insulitis in a model of diabetes. There is also data to support the concept of inhibiting this interaction for the treatment of rheumatoid arthritis and IBD. With respect to the later neutralizing OX40L using OX40-Ig or anti-OX40L monoclonal antibody has produced quite remarkable results, blocking the development of experimental colitis

Dwarfing the autoimmune sector, cardiovascular disease has been the leading therapeutic category for over two decades and is set to continue its pace of expansion and dominance over the global drugs market. The cardiovascular market has expanded from a value of $60 billion in 1997 to $351.8 billion in 2003. With new drugs in the pipeline, competition in the cardiovascular market has never been greater (see The Cardiovascular Report).

One area of the cardiovascular disease arena focuses on inflammation as an etiological factor in disease progression as well as a therapeutic target. For example in Autoimmune Disorders & Transplant Rejection we discuss the prothrombotic effect of CD154 and also the atherogenic activity associated with CD40:CD154. In today’s edition of DailyUpdates (Jan 31st, 2006) we highlight data suggesting that OX40:OX40L represents a further example of how a T-cell co-stimulatory molecule may contribute to heart disease.

A Nature Genetics paper published last year (37(4):365-72) reported on Ath1, a quantitative trait locus on mouse chromosome 1 that impacts on atherosclerosis. The quantitative trait locus region encompasses 11 known genes, including the gene coding for OX40L. Mutating this gene was found to limit atherosclerotic lesions while its overexpression exacerbated atherosclerotic lesions. Moreover, in two independent human populations, polymorphisms in the OX40L genotype increased the risk of myocardial infarction in humans.

In the BBRC paper highlighted today, the same group reported that a polymorphism in intron 5 of the OX40L gene was associated with precocious myocardial infarction. This polymorphism was suggested to affect splicing. OX40L is expressed by activated vascular endothelial cells at sites of inflammation and might as such play a role in extravasations of OX40 positive T-cells. Given the role that immunocytes play in atherosclerosis, alterations in the OX40L:OX40 axis could quite feasibly modify the genesis of heart disease. Although the exact functional consequences of the polymorphism highlighted today requires further study, the therapeutic benefits of targeting OX40L:OX40 interaction may extend past autoimmune disease to encompass the massive area of cardiovascular disease.

Osteoarthritis is a degenerative joint disease occurring mainly in the elderly. It is the most common form of arthritis and according to our feature Disease Modifying Osteoarthritis Drugs - The Search for the 'Holy Grail' Continues this debilitative condition affects over 73 million people in the seven major pharmaceutical markets. Disease modification is currently the ‘holy grail’ in the treatment of osteoarthritis, driven by an aging population and recent success of disease modifiers for rheumatoid arthritis.

One of the major hurdles in reaching this goal is gaining an understanding of the precise mechanism and pathways involved in osteoarthritis. Today’s headline article from DailyUpdates, published in a recent edition of Scand J Rheumatol highlights the involvement of nitric oxide (NO) in osteoarthritis and moreover suggests that disease-modifying anti-rheumatic drugs (DMARDS) developed for the treatment of rheumatoid arthritis may be effective in the treatment of osteoarthritis through the reduction of NO levels.

Although key to a number of physiological processes, excessive NO has been implicated in numerous diseases. Important therapeutic areas for NO-based therapies are inflammatory disorders, cardiovascular diseases, erectile dysfunction, inflammation, pain and neuroprotection. The first therapeutic use of NO was by inhalation for acute respiratory distress syndrome (ARDS).

In the worldwide pharmaceutical market, share of drugs where NO is involved in the mechanism of action is now estimated at $20 billion and is projected to rise to $34.1 billion in 2010 and $52 billion in 2015 as new drugs with NO-based mechanisms are introduced into the market (see Nitric Oxide - Therapeutics, Markets and Companies).
NO is known to be a destructive mediator produced by activated chondrocytes and in their Scand J Rheumatol article, Eeva Moilanen and colleagues reported that four known DMARDs suppressed the production of NO under these conditions. This effect was extended to a reduction in NO production in cartilage from patients with osteoarthritis. This study suggests that therapeutic agents historically used for the treatment of rheumatoid arthritis should also be investigated as treatments of osteoarthritis.

AstraZenaca makes inroads into future treatments of neurodegenerative disease

As discussed in our recent features World Neurodegeneratives Disease Markets, 2005-2009 and Neuroprotection - Drugs, Markets and Companies, treating neural degeneration associated with conditions such as Parkinson's Disease, Multiple Sclerosis and Alzheimer's Disease represents an $5-8 billion market. With the approval of new products, the neuroprotection market value will rise significantly over the next decade.

Stroke, one of the leading causes of death and adult disability worldwide, will also become an increasingly important indication for neuroprotective therapeutics as acute treatments for stroke continue to be limited in their utility (see Neuroprotection in Stroke)

One approach to neuroprotection involves the inhibition of JNK3. The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein (MAP) kinase family, which regulate signal transduction in response to environmental stress. Activation and nuclear localization of JNK3, a neuronal-specific isoform of JNK, has been associated with hypoxic and ischemic damage of CA1 neurons in the hippocampus. In particular, JNK3 has been found to have an upstream role in neuronal ischemic apoptosis implicating it in neural damage following ischemic stroke.

Whilst loss of either JNK1 or JNK2 alone appears to have no serious consequences, their combined knockout is embryonic lethal. In contrast, the loss of JNK3 is not embryonic lethal, but rather protects the adult brain from glutamate-induced excitotoxicity. Thus the development of selective JNK3 inhibitors represents a useful approach to limiting acute neural damage.

JNK3 has also been implicated in several chronic neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. JNK3 is highly expressed and activated in postmortem brains of individuals that suffered from Alzheimer's disease. Furthermore, mice that are deficient in JNK3 are more resistant to the development of disease in an animal model of Parkinson's disease than their wild-type littermates. The involvement of JNK3 in long-term neuronal diseases has therefore extended the potential of JNK3 inhibitors way past that of stroke.

In 1998, Vertex researchers solved the crystal structure of JNK3 and since then a number of companies have screened for selective JNK3 inhibitors. The most recent data to emerge has come from AstraZeneca and this is the subject of the Bioorg Med Chem Lett paper headlined in DailyUpdates (Jan 26th, 2005).

In this paper Swahn and colleagues from AstraZeneca report on the design and synthesis of a new series of JNK3 inhibitors. The rationally designed series was based on a combination of hits from high throughput screening and X-ray crystal structure information of compounds crystallized into the JNK3 ATP binding active site. This series displays selectivity against JNK1 and further development is eagerly awaited.

Supercomputers used to go from genome to lead in under a month

Genomics and proteomics comprise a fundamental area of bioinformatics however exploiting the wealth of information gained using such disciplines remains a rate limiting step in the drug discovery process. Today’s edition of DailyUpdates (Jan 25^th 2005) describes ground breaking work that has allowed researchers to identify candidate therapeutics for the treatment of SARs virus infection in under a month using the virus genome as a starting point

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As information technology becomes increasingly important in drug R&D, the application of bioinformatics/informatics applications has the potential to drive growth in the worldwide pharmaceuticals drug market from the $240 billion today to $3 trillion by 2020.

The role of bioinformatics/informatics in the drug development sector was evaluated in our 2003 feature Bioinformatics/Informatics - Reducing Drug Discovery and Development Costs. The forecasted value for the worldwide informatics market in the life science sector is between $1.7 and $7 billion by 2007.

Genomics and proteomics comprise a fundamental area of bioinformatics (Addressing Pharma’s R&D Productivity Crisis) however exploiting the wealth of information gained using such disciplines remains a rate limiting step in the drug discovery process. A good example of this problem and a novel approach to its resolution has recently been reported by Yuan-Ping Pang and colleagues Andrea J. Dooley and Jewn-Giew Park at the Mayo Clinic and Nice Shindo and Barbara Taggart at the Southern Research Institute in Alabama.

In the February edition of the journal Bioorganic & Medicinal Chemistry Letters Yuan-Ping Pang and colleagues present how they have developed a genome-to-drug-lead approach to identify a candidate treatment of infection with the coronavirus (SARS-CoV) associated virus.

SARS-CoV infection results in the severe acute respiratory syndrome (SARS), an emerging infectious disease with severe mortality. The sequencing of the SARS-CoV genome just 31 days after the outbreak demonstrated just how far the scientific community has progressed in the use of genomics. The failure of this information to be harnessed to develop therapeutic candidates has equally highlighted that exploiting genomic information is sub-optimal. One of the reasons for this bottle-neck is the reliance on expression of encoded proteins and screening of candidate therapeutics that interact with these proteins. Screening can involve in vitro approaches or in silico docking approaches although the latter traditionally requires determination of the crystal structure of the target protein.

The SARS-CoV genome encodes a chymotrypsin-like cysteine proteinase (CCP) that proteolytically processes polypeptides required for viral replication and transcription, representing an ideal drug target for treating SARS. Although small-molecule inhibitors of CCP have been identified, the development of these inhibitors as clinical drugs for treating SARS has not yet been achieved. New inhibitor leads of CCP are thus required.

Yuan-Ping Pang and colleagues were able to model the flexible loop of CCP in its bound state thus predicting its structure obviating the need to resolve its crystal structure. In essence this modeling involved the prediction of 100,000 possible structures for the flexible loop of CCP from its genomic sequence by performing multiple molecular dynamic simulations of the interaction of CCP with its substrate. An average of the 100,000 predicted structures was then used as a target to screen for drug candidates. The challenge behind such modeling is the required computing power; the present study was conducted using a dedicated 1.1 terascale system (terascale refers to computational power beyond a "teraflop" - a trillion calculations per second). With such power the simulations took 20 days.

Vitual resolution of the structure of CCP was validated as an approach by using it as a drug target in virtual screening for small-molecule inhibitors, using a computer docking program, EUDOC. Virtual screening of 361413 small molecules identified 3958 candidate hits; 12 of these were selected for cell-based inhibition assays. Five out of 12 tested were active. One compound, CS11, inhibited the human SARS-CoV Toronto-2 strain with an EC50 of 23 microM; CS11 was not toxic to normal cells. The use of EUDOC allowed the prediction of strategies for lead optimization.

These results demonstrate that, given the SARS-CoV genome only, one can identify a small molecule that is able to penetrate cells and rescue them from viral infection, leapfrogging the experimentally determined structures of CCP. In this study, the 3D model of CCP was predicted from the genome in just 20 days and an excellent inhibitor lead for CCP was identified by virtual screening in 9 days. The potential of such an approach is obviously staggering however before companies are able to exploit such power they will either have to purchase terascale computing systems (currently costing in excess of $50 million) or form collaborations with institutions that already have access to such systems (Yuan-Ping Pang built his own terascale computer systems with less than $1 million).

Something borrowed...something blue…something old…something new: The obesity therapeutics market evolves

Today's edition (Jan 24th) of DailyUpdates highlights major advances in the treatment of obesity

The problem of obesity is well recognized. Defined as a BMI of above 30 (compared to 18.5-25 for healthy individuals), obesity is generally caused by poor dietary habits resulting in the ingestion of excessive eat sugar and fat. When intake exceeds requirement the individual becomes overweight. Although diet is the major influence on weight gain there is a genetic influence and genes are thought to contribute 25–40% to obesity. A number of gene defects have been linked to obesity such as mutations in the genes encoding leptin, the melanocortin-4 receptor, cholesterol side-chain cleavage enzyme and PPAR gamma.

Something old….In our recent feature Obesity - commercial opportunities and therapeutic pipeline analysis it is estimated that there are 127 million obese people in the seven major markets and numbers are expected to increase. In 1997 the FDA approved Abbott’s Meridia (sibutramine) for the treatment of obesity and of the currently available approved therapeutics, this agent has been on the market the longest. Meridia acts centrally, inhibiting the reuptake of norepinephrine, serotonin and dopamine.

Something blue….More recently, the FDA approved a second therapeutic, Roche’s Xenical (Orlistat). In contrast to Meridia, this blue tablet acts peripherally by blocking lipase activity thus reducing lipid absorption. Approved in April 1999 Orlistat has now grown to one of Roche’s most successful drugs. In 2004 it ranked #8 amongst Roche’s bestsellers bringing in 593 million Swiss Francs (approx $0.5 billion). Roche generates roughly a quarter of Xenical's worldwide sales in the US.

Something borrowed….In the same year, Roche and GSK penned an agreement under which the North American Consumer Healthcare division of GSK agreed to pay Roche Holdings $100 million for the rights to sell Orlistat over the counter in the US. Roche retained control of the prescription versions (GSK currently markets Orlistat in the US) and will retain over-the-counter rights outside the United States. GSK in-licensed Orlistat prior to winning FDA approval for the OTC version and today’s announcement that this approval has been recommended represents a major advance.

Press releases posted on the websites of GSK and Roche (and which headline today’s edition of DailyUpdates), announce that the FDA joint Nonprescription Drugs and Endocrinologic and Metabolic Drugs Advisory Committee recommended that Orlistat 60 mg capsules be approved for over-the-counter use in the US to promote weight loss in overweight adults, when used along with a reduced calorie, low-fat diet. If approved by FDA, OTC Orlistat (named Alli) would be the only FDA-approved weight loss drug available over the counter.

Something new….In addition to highlighting the developments around Alli, today’s edition of DailyUpdates also reports on a potential new molecular target for future obesity treatments. This target, aquaporin 7 is investigated in a paper in this month’s edition of BBRC. The paper (Biochem Biophys Res Commun. 2006 Jan 20;339(3):785-9) reports that the gene encoding aquaporin 7, AQP7, is down-regulated in obese compared to lean subjects.

Aquaporins are integral membrane proteins that facilitate water movement across the cell membrane. Some of the aquaporins are also known to permeabilize glycerol as well as water. AQP7 is one such protein (also known AQP adipose AQPap) first identified in 1997. Triglycerides in adipocytes are hydrolyzed to fatty acids and glycerol, and both are released into the circulation. Loss of AQP7 results in reduced release of glycerol both in humans and mice. Loss of AQP7 also produces adult-onset obesity and insulin resistance in rodents, a finding that was mirrored by adipocyte hyperplasia and triglycerides accumulation. The molecular mechanism underlying these events appears to involve elevated adipose glycerol kinase activity and accelerated triglycerides synthesis in adipocytes.

The BBRC findings highlighted today suggest that AQP7 may also be implicated in human obesity suggesting that activators of this channel could be of interest therapeutically.

Busting clots and killing tumors.

In today’s edition of DailyUpdates we feature news on Nuvelo’s candidate for cardiovascular disease, alfimeprase, plus breaking research on thioredoxin inhibitors for the treatment of cancer .

Our headline press release concerns the development of Nuvelo’s candidate treatment for acute peripheral arterial occlusion (also known as acute limb ischemia), alfimeprase. This announcement comes on the same day that we release an in depth report on this field by our partners at The Sage Group (Acute Limb Ischemia Acute Limb Ischemia - A market of multiple therapies and multiple procedures)

Acute limb ischemia is a common yet unmet condition representing the most serious form of peripheral arterial disease (PAD) and is caused by a sudden decrease or worsening of limb perfusion following thrombosis or an embolism (usually in patients with atrial fibrillation). Caused by smoking, diabetes and other risk factors that precipitate peripheral arterial disease, acute limb ischemia is associated with high mortality and amputation rate. Within the first 30 days of ischemia, up to 15% of patients will die while as many as 30% will suffer amputation. These rates rise dramatically over time with mortality reaching over 60% within 5 years, worse than in patients with other cardiovascular diseases or the most common malignancies.

Depressingly, one of the primary treatments of acute limb ischemia is amputation, which represents the first line approach in as many as 70% of patients, a hugely worrying statistic given the cost and reduced quality of life associated with such procedures. More conservative approaches represent a clearly unmet area usually comprising a multi-modal strategy of anticoagulant therapy, surgery (usually embolectomy or bypass), or clot disruption. The benefits of embolectomy (distension of the blocked vessel using a balloon catheter) are frequently limited in acute limb ischemia and instead thrombolytic and interventional approaches to clot removal are more useful.

Although thrombolytic therapy is well practiced in cardiovascular medicine no thrombolytics have yet been approved for the treatment of acute limb ischemia. This is worrying considering the prevalence of disease. Figures from 1997 suggest that 50,000 in the US suffer acute limb ischemia however as discussed in our feature, these numbers are a gross underestimation. Nuvelo seem to be making important headway in this condition with the development of Alfimeprase (currently in phase III studies).

Alfimeprase a recombinant protein able to directly degrades fibrin within thrombi. In clinical studies to date, alfimeprase has been shown to resolve peripheral arterial clots within four hours of initiation of dosing. In addition, its lytic activity is localized to the site of delivery due to its rapid inhibition by endogenous alpha-2 macroglobulin.

Alfimeprase is also in development for the potential treatment of catheter occlusion, clearing occluded catheters in 15 minutes or less; it and may have utility in a wide range of additional thrombotic-related conditions such as stroke, deep venous thrombosis and myocardial infarction. In their report The Sage Group forecast that Alfimeprase will be generating over $300 million in US sales by 2010 for the treatment of acute limb ischemia alone.

Also headlined in DailyUpdates today is a Clin Cancer Res paper that reports an association between thioredoxin and drug resistance in breast cancer patients.

In the course of normal metabolism, oxidizing equivalents or reactive oxygen species (ROS) are generated when oxygen is partially reduced as electrons leak out of the electron transport chain during respiration in mitochondria. Other endogenous enzyme systems also produce ROS and overly high levels of these molecules can produce cytotoxic "oxidative stress". To counteract the effects of oxidative stress, cells have developed defense mechanisms including glutathione, thioredoxin and various enzymes such as superoxide dismutase, catalase, and glutathione peroxidase.

Certain chemotherapeutic agents used in the treatment of cancer increase ROS levels thereby killing tumors, an effect that can be reversed by artificially increasing thioredoxin levels. Elevated levels of thioredoxin have also been observed in several human bladder and prostatic cancer cell lines resistant to chemotherapy. The Clin Cancer Res paper takes these observations forward demonstrating a role of thioredoxin in drug resistance in primary breast cancer samples.

Kim and colleagues demonstrate that docetaxel produced a lower response rate in tumors with high thioredoxin expression compared to those with low thioredoxin expression. Furthermore thioredoxin expression significantly increased after docetaxel therapy. These data suggest that inhibiting thioredoxin may be a useful approach to improving the efficacy of chemotherapy and indeed, in today’s DailyUpdates we report on an announcement by ProlX Pharmaceuticals' who have just enrolled the first patient in a Phase IB clinical trial of their thioredoxin inhibitor, PX-12, in patients with advanced gastrointestinal cancers.

PX-12 has shown encouraging safety and efficacy data in an initial Phase I trial and it is hoped that this will be extended into more advanced studies.

From cannabinoids to protein kinases

DailyUpdates 20th January, 2006 - What's new in drug development: Today we feature 25 journal articles and 4 press releases selected for the drug development sector.

The pick of the featured journal articles (at least in our mind) concerns a novel approach to cannabinoid based pharmaceuticals.

As discussed in our recent report, Cannabinoids - A potential Blockbuster, cannabinoid receptor ligands have the potential to become blockbusters although only two products are available in this growing market. This will soon be changed with the imminent approval of Sativex (see our featured release from Jan, 2006), and the mid-2006 launch of Acomplia by Sanofi-Aventis. Further development continues with Pharmos recently announcing (press release) the initiation of phase II trials of their CB2 ligand for the treatment of pain (this market is discussed in Pain Therapeutics - Drugs, Markets and Companies).

One problem with the cannabinoids, in particular CB1 agonists, is that they can produce a spectrum of motor and psychotropic side effects. Fatty-acid amide hydrolase (FAAH) is involved in the degradation of endogenous cannabinoids and today's headline article (Br J Pharmacol. 2005 Dec 5; [Epub ahead of print]) reports that a selective FAAH inhibitor, URB597 displays efficacy in models of pain without altering motor performance as a result of CB1 and CB2 receptor activation.

Our headline press release announces a new assay kit that should be of use to many in the drug development sector.

The various protein kinases families continue to provide key molecular targets across a broad range of therapeutic areas. Only yesterday we featured new data from AstraZeneca emerging from their efforts to develop inhibitors of aurora kinase (we have evaluated this subfamily of promising oncology targets in a recent report - click here). The protein kinases as a whole are evaluated in a second feature The Emerging Drug Targets Outlook.

One of the limiting factors in exploiting this family therapeutically is the availability of screening tools and today's press release from NovaScreen described new assays that should hopefully ease this problem.

That all for today...to see today's DailyUpdates bulletin in its entirety please click here

BAFF & APRIL: Emerging Targets for Autoimmune & Cancer Therapeutics

In 1999 Human Genome Sciences researchers published a study in the journal Science describing a new member of the TNF super-family which they named BLyS. Since that time our understanding of this protein, also known as BAFF, and its homologue APRIL has progressed rapidly. The BAFF sub-family has emerged as a candidate target for therapies of various autoimmune diseases and hematological cancers with breathtaking speed.
In April 2005, LymphoStat-B, HGS' neutralizing anti-BAFF monoclonal antibody, met the primary efficacy and safety endpoints in a Phase 2 clinical trial in patients with rheumatoid arthritis. A few months later a Phase 2 study also demonstrated efficacy in systemic lupus erythematosus. Earlier this month Zymogenetics announced Phase 1 data on TACI-Ig, a decoy receptor designed to block APRIL and BAFF. This molecule is also showing promising activity in hematological cancers.

The continuing success of Rituxan has established a proof of concept for the development of B-cell targeted therapeutics as treatments of a broad range of autoimmune disorders and hematological cancers and global annual sales are now well in excess of $2 billion. Therapeutics targeting the BAFF sub-family stand to offer significant competition to Rituxan yet advanced development is currently restricted to LymphoStat-B and TACI-Ig. LeadDiscovery’s analysts believe that this drug class is far from optimized, offering companies with an interest in autoimmune disease or cancer significant opportunities.

In the wake of the emerging success of therapeutics such as LymphoStat-B and TACI-Ig our pharmaceutical analysts have produced an in depth drug discovery report BAFF & APRIL: Emerging Targets for autoimmune & Cancer Therapeutics

Some of our key conclusions are:

* There is particularly good evidence to support a role of BAFF in the etiology of rheumatoid arthritis although based on cross-study comparison the efficacy of the lead therapeutic in this class, LymphoStat-B, appears to be inferior to Rituxan. LymphoStat-B blocks just BAFF however APRIL is also elevated in the synovial fluid of rheumatoid arthritis patients. We conclude that dual blockade of APRIL as well as BAFF may be required for optimal therapeutic activity. Data from ZymoGenetic’ study of TACI-Ig may shed some light on this issue.

* Immunosuppressive adverse effects of BAFF/APRIL blockers should be less than those resulting from Rituxan

* Blocking BAFF and/or APRIL may be a useful adjuvant to TNF blockers, increasing efficacy while possibly reducing the heightened risk of lymphoma associated with this major therapeutic class.

* There is good evidence to suggest that BAFF contributes to the etiology of systemic lupus erythematosus however optimal selectivity of therapeutic agents aimed at BAFF remains to be established.

* Of all the autoimmune conditions investigated, the serum levels of BAFF are highest in Sjögren's syndrome. One particularly attractive advantage of blocking BAFF and/or APRIL is that this approach may prevent the development of lymphomas, a co-morbidity associated with a subgroup of patients.

* Other autoimmune diseases that have yet to fall under the spotlight of BAFF/APRIL should be evaluated as target indications. In particular multiple sclerosis and inflammatory bowel disease may represent potential indications.

* Strong evidence supports the blockade of BAFF/APRIL as a treatment of multiple myeloma and non-Hodgkin’s lymphoma. Elevated levels of these molecules may limit the efficacy of existing therapeutic agents, while their blockade is likely to act in an additive or possible synergistic fashion with steroids or IL-6 therapeutics.

Already interest in this report is strong and hopefully this indicates that further companies are entering the field of BAFF. This can only lead to further optimization of therapeutics from this class.

If you have found this post interesting you may also be interested in another one of our recent reports Autoimmune Disorders & Transplant Rejection